The solenoid used in a housing, subject to vibration, to move a machine element on command and bold the selected position when acceleration forces urge it to move relative to the housing represents the typical problem area to which apparatus of this invention is directed. The solenoid armature and the payload it is expected to move represents mass. If the housing is subjected to a displacing acceleration in a selected direction, the stated mass tends to move in the opposite direction relative to the housing. If the mass moves in response to the acceleration it may produce erroneous movement of switches, valves, and the like.
If adequate space and power are available there are many ways to prevent unwanted acceleration induced movement. Brakes, detents, viscous damping, holding magnets and various secondary latching systems can be used. When power and space are limited, compensation becomes more important. Constant drag brakes require power to overcome when purposeful movement is required. Even if mass restraining devices can be released in preparation for intended movement the acceleration may impose added burden if the direction to be moved is against acceleration forces. If timing is critical, movement against acceleration forces in one actuation and with acceleration forces in the next actuation may result in prohibitive timing variances.
The small instrument systems used in drill strings in wells being drilled, for the purpose of measurement while drilling communication, have forced the compensation matter to attention. For many years apparatus bas been needed to compensate for the displacement forces imposed upon movable elements in a machine subject to acceleration forces. Apparatus of this invention effectively doubles the mass of the element to be purposefully moved against acceleration forces and retained in selected positions irrespective of such forces but otherwise protects against influence of acceleration of the host machine and defines the principal object of this invention
It is therefore an object of this invention to provide apparatus for use in vibration and shock environment to enable control elements having weight to function without excessive influence from the resulting acceleration reaction forces.
It is another object of this invention to provide acceleration compensator assemblies for use in apparatus used downhole in drilling operations to reduce the influence of acceleration forces upon activity control machine members.
It is yet another object of this invention to provide well bore communication drilling fluid pressure change generators with acceleration compensation apparatus to prevent erroneous signal generation resulting from acceleration reaction caused by shock and vibration.
These and other objects, advantages, and features of this invention will be apparent to those skilled in the art from a consideration of this specification, including the attached claims and appended drawings.